Editing Group 12 element (section)

===Cadmium===
In 1817, cadmium was discovered in Germany as an impurity in [[zinc carbonate]] minerals (calamine) by [[Friedrich Stromeyer]] and [[Karl Samuel Leberecht Hermann]].<ref>{{cite book|chapter = Cadmium |title = Kirk-Othmer Encyclopedia of Chemical Technology |edition = 4th |place=New York |publisher = John Wiley & Sons |year=1994 |volume= 5}}</ref> It was named after the Latin ''cadmia'' for "[[calamine]]", a cadmium-bearing mixture of minerals, which was in turn named after the Greek mythological character, Κάδμος [[Cadmus]], the founder of [[Ancient Thebes (Boeotia)|Thebes]].<ref>{{cite journal|journal = Annalen der Physik|year = 1818|pages = 113–116|volume = 59|title = Noch ein schreiben über das neue Metall (Another letter about the new metal)|author = Hermann|url = http://gallica.bnf.fr/ark:/12148/bpt6k150680/f125.chemindefer|bibcode = 1818AnP....59..113H |doi = 10.1002/andp.18180590511|issue = 5 }}</ref> Stromeyer eventually isolated cadmium metal by [[Roasting (metallurgy)|roasting]] and reduction of the [[cadmium sulfide|sulfide]].<ref>{{cite book|url = https://books.google.com/books?id=84VAAAAAYAAJ&pg=PA122|page = 122|title = Cyclopædia of commerce, mercantile law, finance, commercial geography and navigation|author1 = Waterston, William|author2 = Burton, J. H|year = 1844}}</ref><ref>{{cite book|url = https://books.google.com/books?id=Q-cHAAAAQAAJ&pg=PA10|page = 10|title = The art of landscape painting in water colours, by T. and T. L. Rowbotham|author1 = Rowbotham, Thomas Leeson|year = 1850}}</ref><ref name="Cadold">{{cite book|pages = 135–141|url = https://books.google.com/books?id=gGHOz1G3AqwC&pg=PA135|title = The life cycle of copper, its co-products and byproducts|isbn = 978-1-4020-1552-6|author1 = Ayres, Robert U.|author2 = Ayres, Leslie|author3 = Råde, Ingrid|year = 2003| publisher=Springer }}</ref>

In 1927, the [[Bureau International des Poids et Mesures|International Conference on Weights and Measures]] redefined the meter in terms of a red cadmium spectral line (1 m = 1,553,164.13 wavelengths).<ref>{{cite journal|title = On the new determination of the meter|journal = Measurement Techniques|volume = 1|issue = 3|year = 1958|doi = 10.1007/BF00974680|pages = 259–264|first= G. D.|last = Burdun| bibcode=1958MeasT...1..259B |s2cid = 121450003}}</ref> This definition has since been changed (see [[krypton]]). At the same time, the [[International Prototype Meter]] was used as standard for the length of a meter until 1960,<ref>{{cite journal |url=https://nvlpubs.nist.gov/nistpubs/jres/104/3/j43bee.pdf |title=The NIST Length Scale Interferometer |volume=104 |issue= 3 |date=May–June 1999 |journal=Journal of Research of the National Institute of Standards and Technology |first1=John S. |last1=Beers |first2=William B. |last2=Penzes |page=226|doi=10.6028/jres.104.017 |s2cid=2981956 }}</ref> when at the [[General Conference on Weights and Measures]] the meter was defined in terms of the orange-red [[emission line]] in the [[electromagnetic spectrum]] of the [[krypton]]-86 atom in [[vacuum]].<ref name=Marion>{{cite book|last=Marion|first=Jerry B.|title=Physics For Science and Engineering|year=1982|publisher=CBS College Publishing|isbn=978-4-8337-0098-6|page=3}}</ref>